NEUROCHEMICAL STUDIES IN GENETIC MODELS OF EPILEPSY

这项研究的目的是研究神经化学， 癫痫的生理和遗传机制在两个不同的 癫痫的遗传小鼠模型。 这些老鼠包括 听源性癫痫（AGS）易感DBA/2（D2）小鼠（ 全身性失神发作）和E1（癫痫）小鼠（模型 颞叶癫痫）。 先前的证据表明， D2小鼠的易感性在遗传上与 脑外Ca 2 +-ATP酶活性缺乏。 高AGS 易感性和低脑外Ca 2 +-ATP酶活性， 在由各种杂交产生的F1杂种中一起遗传 菌株 这种胞外Ca 2+的生化基础。 atp酶 缺陷目前尚不清楚。 以确定是否减少 D2小鼠中的活性是由于 酶的动力学特性进行了研究 在D2小鼠的微粒体和突触质膜中， 癫痫抗性C57 BL/6（B6）和F1杂交小鼠。 我们建议 胞外Ca ~（2+） ATP酶是快速水解 D2小鼠释放的ATP及其缺乏有助于癫痫发作 通过允许ATP在突触中保持活性， 裂缝 这一假设得到了最近B6和 D2海马切片，并将在B6 x D2中进一步研究 重组近交系;哺乳动物中的有力分析工具 遗传学 初步研究还表明， 对于AGS，aspl与Ah基因座和一种新的限制性内切酶相关联， 12号染色体DNA片段长度多态性。 的相对 这些基因的位置将使用孟德尔回交作图 代 因为这是第一个已知的基因连锁 一个DNA多态性和一个癫痫基因， 癫痫的分子遗传学 中的一个重要问题 癫痫研究一直难以解决的问题， 与病因相关的神经化学缺陷 癫痫发作和缺陷与反复的影响， 癫痫活动。 已经在E1小鼠中开发了一种范例来处理 解决这个问题 由于我们的初步结果表明，E1小鼠 在海马中表达反应性胶质增生， 小脑神经节苷脂GD 3和天冬氨酸释放增加 在海马切片中，该范例将用于确定是否 这些缺陷是海马中天冬氨酸释放增加， 切片，此范例将用于确定这些缺陷是否 与癫痫发作的原因或后果有关。 因为 D2和E1小鼠的癫痫发作是自然发生的， 与这些癫痫发作相关的缺陷将是相关的基本 癫痫的发病机制

The purpose of this research is to study the neurochemical, physiological and genetic mechanisms of epilepsy in two different genetic mouse models of epilepsy. These mice include the audiogenic seizure (AGS) susceptible DBA/2 (D2) mouse (a model for generalized absence seizures), and the E1 (epilepsy) mouse (a model for temporal lobe epilepsy). Previous evidence indicates that AGS susceptibility in D2 mice is genetically associated with a deficiency of a brain ecto-Ca2+-ATPase activity. High AGS susceptibility and low brain ecto-Ca2+- ATPase activity are inherited together in Fl hybrids produced from crossing various strains. The biochemical basis for this ecto-Ca2+. ATPase deficiency is presently unknown. To determine if the reduced activity in D2 mice results from a qualitative defect in the enzyme, kinetic properties of the ecto-Ca2+-ATPase will be studied in microsomes and synaptic plasma membranes of the D2 mice and the seizure resistant C57BL/6 (B6) and Fl hybrid mice. We suggest that the ecto-Ca2+. ATPase is essential for the rapid hydrolysis of released ATP and its deficiency in D2 mice contributes to seizure susceptibility by allowing ATP to remain active in the synaptic cleft. This hypothesis is supported from recent studies in B6 and D2 hippocampal slices and will be studied further in B6 x D2 recombinant inbred strains; a powerful analytical tool in mammalian genetics. Preliminary studies also indicate that the major gene for AGS, aspl, is linked to the Ah locus and to a novel restriction fragment length DNA polymorphism on chromosome 12. The relative location of these genes will be mapped using mendelian backcross generations. Since this is the first genetic linkage known between a DNA polymorphism and an epilepsy gene, insight can be obtained on the molecular genetics of epilepsy. An important problem in epilepsy research that has been difficult to resolve concerns the distinction between neurochemical defects associated with the cause of seizures and defects associated with the effects of repeated seizure activity. A paradigm has been developed in E1 mice to deal with this problem. Since our preliminary results show that E1 mice express a reactive gliosis in hippocampus, and elevated content of ganglioside GD3 in cerebellum, and elevated aspartic acid release in hippocampal slices, this paradigm will be used to determine if these defects are elevated aspartic acid release in hippocampal slices, this paradigm will be used to determine if these defects are associated with the cause or effect of seizures. Because the seizures in the D2 and E1 mice occur naturally, the neurochemical defects associated with these seizures will be relevant basic mechanism of epilepsy.